N = int(input())
A = list(map(int,input().split()))
k = []
c = []
count = len(A)
while count > 0:
    if count == len(A):
        for i in range(len(A)):
            k.append(A[i])
        count -= 1
    else:
        for i in range(len(k)-1):
            c.append(k[i]+k[i+1])
        k = c
        c = []
        count -= 1
print(int(k[0])%(10**9+7))